I'm not sure about your exact Amber organization and setup, but you say that
AMERHOME=/Users/george/Programs/amber11/

Yet, ptraj is being found here: /Users/tzotzos/Programs/amber11/bin/ptraj.
This appears to be finding a different Amber 11 installation than the one
that you say is AMBERHOME. Is sander found
in /Users/tzotzos/Programs/amber11/bin/ ? Do you have two different
AMBERHOME's defined somewhere?